Why polar bears are white? - Evolution

Evolution is the most perfect, relentless and unforgiving system ever. In other words, an ice-hearted b*ch. It can easily explain almost all physical, behavioral and psychological traits you can think of. You don’t believe? Ask in the comments and I will explain you trait using the evolution theory. For example it can explain why polar bears are white, why eggs are not completely spherical, why you have wisdom teeth, why you have goosebumps and why babies grab your finger really strong. You want to know? Keep reading!

_{Cute polar bear. Noticeably white due to natural selection in a snowed environment. Source: https://polarbearsinternational.org/news/article-research/polar-bear-point-of-view-videos/} .

It is just a theory. JUST?

I am not going to start the evolution vs. creationism debate here, although I will happily and respectfully obliterate creationists in the comments. However, I often hear that evolution is just a theory.

Every time you let go a ball it falls down. And actually it always falls accelerating at 9.82 m/s2 (if friction is not considered). You can try as many times as you want, the ball always falls. That is a fact. Gravity is just the theory that explains this fact. In the same way, we have found fossils, we have observed DNA mutations, we have seen how reproduction works and using logic we have come up with the best theory to explain these facts.

_{Richard Dawkings giving creationist what they deserve. Source: https://iwastesomuchtime.com/52564} .

Natural selection

Before we explained the facts mentioned at the beginning let’s see how the basic mechanism works. The Neo-darwinian theory explains the selection of the fittest. Watch out! I said fittest, not strongest. In evolution the important thing is to fit the environment, hence it is a relative concept, not everyone evolves in the same direction. The fittest organism in an environment will have advantage in relation to others.

For example, a white bear (a.k.a polar bear) in the North Pole will be able to approach its pray unseen while a brown bear will be easily spotted and its pray will escape. Hence, a white bear would be able to feed, to have more energy and thus highest chances of surviving long enough to mate and have descendants.

And descendants are the only goal in any organism’s life. – Why?- Because every trait is encoded in DNA (for example, the white color for polar bears) which is the only thing that is passed onto descendants. Hence, bears with the white gene will have more children than browner bears (only in snowy environments, where they have advantage), and this children will be white because they will have the white gene. Now you can see that the bear population in the North Pole will turn to white until only white bears remain.

The environmental pressure exerted on organisms, for example snow, water, temperature, the type of soil… leads to the selection of certain traits. This process of selection is called natural selection.

The intelligent design: a misinterpretation

Now, it is very important to understand that white bears are selected because of the presence of snow, but do NOT appear because of the snow. The snow is NOT related to the appearance of the first white bear, it merely selected it. – Then how did the first polar bear come to be? - That is the Question. The answer: DNA mutations, which are RANDOM.

As I explained in a previous post DNA suffers mutations every time it replicates. Besides, in sexual reproduction half of the male’s DNA is mixed with half of the female’s DNA, leading to new combinations of genes and therefore traits. All this mutation and recombination of genes is utterly RANDOM.

_{A bit of humor. Source: http://the-messiahs-blog.blogspot.com.es/2010/12/pathetic-fallacy-of-intelligent-design.html} .

-Do you mean that it is only by chance that a white bear appeared?-YES. -Then every single biological trait appeared for the first time by chance, including eyes, thumbs, stomach, a tongue, an elephant trunk???-.YES*. -Impossible!!!-. No, calm down, there is a trick. Every mutation appears randomly, but an eye or a tongue are not a single mutation, it required millions of mutations to achieve a current eye or tongue.

For example, the color of the polar bear’s hair is simpler since it depends on only a few genes. However, every gene has thousands of nitrogenous bases and only the right combination of mutations will result in color white. There are trillions of possible combinations.

-Then how comes we have all the right mutations!? It is impossible that we are that lucky! There must be something else, something that made the right mutations more probable to happen or some kind of guided evolution!-. This idea is called Intelligent Design. And it is flawed.

Evolution through random mutations is possible due to a combination of time and natural selection. We are not lucky enough to have the right mutations, trillions died with the wrong mutations, you are just the one who lived. Furthermore, every time an advantageous mutation appears, it is kept in the population through natural selection until it spreads to the whole population or it stops being advantageous and thus, it is eliminated. For example, in a population of bears there might be a few white bears. It is not an advantage or a disadvantage in a normal environment. However, when it starts to snow white bears that already existed have a survival advantage. Thus, the white gene is enhanced in the population.

Another good example to understand this is antibiotic resistance in bacteria, which is a very dangerous phenomena. Imagine you get an infection in which there are millions of bacteria. You take some antibiotic that kills 99.999% of one million. You still have 100 which were resistant to the antibiotic because they had the right mutation. Now, this 100 bacteria have a lot less competition for resources than they had before you used the antibiotic and will grow much faster with all their descendants being resistant to the antibiotic.

_{Representation of how antibiotic resistance works. Source: https://www.reactgroup.org/toolbox/understand/antibiotic-resistance/mutation-and-selection/}

Still, the biggest mistake in the intelligent design theory is the scale of time. Life started more or less 3900 millions of years ago. Your brain cannot process this number, the number of generations of organisms that have lived is enough to justify evolution.

Next post

Tomorrow I will post a short article explaining the facts I mentioned in the first paragraph, since this article is getting too long. But I would like to take this to the next level by offering you a challenge. In the next article I will propose a challenge and whoever beats me will receive 1 steem dollar!

Hope you liked it! Follow me for more articles about biology and biotechnology! Check out my other articles if you are interested and feel free to ask your questions in the comments or propose a topic that you like!

• DNA – What is exactly DNA and how does it work?
• DNA II – How does DNA replicate itself?
• GMO (Genetically modified organisms) – Damnation or salvation? Debate
• Organic robots & the code of life